Method of manufacturing fine metallic filaments

ABSTRACT

A method of producing fine metallic filaments by covering a bundle of a plurality of metallic wires with an outer tube metal and drawing the resultant composite wire, wherein the outer tube metal on both sides of the final composite wire obtained after said drawing step is cut near to the core filaments present inside the outer tube and then both uncut surfaces of the composite wire are slightly rolled, thereby to divide the outer tube metal of the composite wire continuously and thus separating the outer tube metal from fine metallic filaments. The separation treatment can be effected by a simple apparatus within short time. This reduces the cost of production, and enables the outer tube metal to be recovered in situ.

Tada et al.

[ Jan. 15, 1974 METHOD OF MANUFACTURllNG FINE METALLIC FILAMENTS [75] Inventors: Yoshiyuki Tada; Hideo Ogita;

Takeshi Yoda, all of ltami, Japan [73] Assignee: Sumitomo Electric Industries, Ltd.,

Higashi-ku, Osaka, Japan 221 Filed: May 17, 1972 211 Appl.No.:254,124

[30] Foreign Application Priority Data 3,394,213 7/1968 Roberts et a1. 29/419 X 2,827,405 3/1958 Evans et a]. 29/426 2,894,868 7/1959 Hyde 8l/9.51 X 3,641,852 2/1972 Terada 8l/9.51 X

Primary ExaminerChar1es W. Lanham Assistant ExaminerD. C. Reiley, III Attorney-Richard C. Sughrue et a1.

[5 7 ABSTRACT A method of producing fine metallic filaments by covering a bundle of a plurality of metallic wires with an outer tube metal and drawing the resultant composite wire, wherein the outer tube metal on both sides of the final composite wire obtained after said drawing step is out near to the core filaments present inside the outer tube and then both uncut surfaces of the composite wire are slightly rolled, thereby to divide the outer tube metal of the composite wire continuously and thus separating the outer tube metal from fine metallic filaments. The separation treatment can be effected by a simple apparatus within short time. This reduces the cost of production, and enables the outer tube metal to be recovered in situ.

2 Claims, 6 Drawing Figures PAIENTEU JAN 1 5 I974 SHIN 10F 2 FIG. 2

FIG. 4

FIG. 3

FIGS

PATENIEUJA" 15 sum 2 w 2 3.185036 1 METHOD OF MANUFACTURING FINE METALLIC FlILAMENTS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method of producing a yarn of fine metallic filaments at low cost, and especially to a novel method of producing a yarn of fine metallic filaments by bundle drawing wherein the outer metal tube of a composite wire is mechanically spearated from core filaments present inside the outer tube.

2. Description of the Prior Art In recent years, fine metallic wires about 0.150 to 0.005 mm in diameter made of carbon steel, alloy steel, stainless steel, etc. or yarns or slivers thereof have found applications as tire cords, metallic fibers for blending purposes, or fine metallic fibers for filters, etc. Generally, in the single wire drawing process using a die, the production of fine metallic filaments must be performed by the repetition of heat-treatments and drawings, and the productivity is low. This leads to an extreme increase in the cost of production. In an attempt to overcome these disadvantages, the bundle drawing process was devised, and has been utilized to some extent.

The conventional bundle drawing method comprises first coating the surface of material wires with a separator such as a metal oxide, graphite or an oil, which prevents the metallic bonding of the wires during the drawing and heat-treatment operations, or with a different metal by, for example, plating; inserting a bundle of a plurality of such material wires in a tube of a different metal, or covering this bundle of wires with a metallic tape at its outer circumference, and welding the seam portion thereby to form a composite Wire; subjecting the composite wire to a diameter reduction treatment by drawing, and heat-treatment, etc. until the diameter of each filament reaches a certain desired value; and thereafter, dissolving the outer metal tube alone or together with the coated metal by a chemical method, and separating them from the core filaments, thereby obtaining fine metallic filaments.

According to this prior art method, the outer metal tube (A) alone or together with the coated metal (B) should be dissolved by dipping or electrolysis using a specially selected reagent solution which does not react with the fine metallic filaments present inside the tube, but reacts only with (A) or with (A) and (B) (A and B may be the same kind of metal). This dissolving operation generally takes a long time and requires strict control of the conditions; Furthermore, because of using a special chemical solution, the cost of production increases, and the recovery of the dissolved metal is difficult.

Accordingly, an object of this invention is to provide a method of producing fine metallic filaments by the bundle drawing method wherein the separation of the outer metal tube of the drawn composite wire is effected by a mechanical procedure instead of the conventional chemical procedure, whereby the abovementioned defects of the prior art can be removed, and the separation treatment of the fine metallic filaments of the composite wire can be performed by a simple ap paratus within a shorter time, which reduces the cost of production, and whereby the recovery of the outer tube metal can be simultaneously performed in situ.

Another object of this invention is to provide a method of producing fine metallic filaments wherein by the mechanical procedure used for the separation treatment instead of the chemical procedure, the fine metallic filaments do not undergo corrosion, and products of good quality without breakage or deterioration in properties can be obtained.

SUMMARY OF THE INVENTION According to this invention, there is provided a method of producing fine metallic filaments by the bundle drawing method, wherein in order to separate the outer tube metal of the final drawn composite wire from the core filaments therein, the outer tube metal on both sides of the composite wire is cut near to the core filaments, and then both uncut surfaces of the composite wire are lightly rolled thereby to divide the composite wire continuously and thus form fine metallic filaments.

The above and other objects of this invention along with the features and advantages thereof will become fully apparent as the description proceeds with reference to the accompanying drawings. Some embodiments of the present invention are illustrated in the drawings, but the invention is in no way limited thereto.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1, 2, 3 and 4 show one example of the process of producing fine metallic filaments in accordance with this invention, FIG. 1 showing a composite wire before drawing, FIG. 2 the composite wire after drawing, FIG. 3 the composite wire after cutting of both sides of the outer tube, and FIG. 4 fine metallic filaments finally obtained.

FIG. 5 is a schematic view of an apparatus to be used for the performance of the present invention to separate the outer tube metal of the drawn composite wire from the core filaments therein; and

FIG. 6 is a sectional view showing the state of cutting the outer tube metal in the apparatus shown in FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In accordance with this invention, as shown in FIG. 1 same as in the above-described conventional method, a separator 2 is coated on the surfaces of material wires 1, or a different metal 2 is coated thereon by, for example, plating. A bundle ofa plurality of the coated material wires is inserted in a tube 3 of a different metal, or the bundle of the material wires is covered with a metallic tape 3 at its outer circumference, followed by welding the seam portion to form a composite wire 4. The separator or metal coated layer 2 on the surfaces of the material wires is not altogether necessary when the material wires are not heat-treated in any subsequent step. Then, the composite wire obtained is subjected to a diameter reduction treatment by drawing, heat-treatment, etc. until the diameter of each core metallic wire 1 reaches a desired value, and a composite wire having the section as shown in FIG. 2 is obtained. The drawn composite wire is subsequently processed by an apparatus of the type shown in FIG. 5. Referring to FIG. 5, the reference numeral 4 represents a drawn compositewire including, for example, 9l high carbon steel filaments with a diameter of 0.050 mm and a mild steel tube having a thickness of 35 to 40 micronmeters covering the outer circumference of a bundle of the steel filaments. A supply reel for the composite wire 4 is shown at 5. The composite wire 4 ispasscd through an outer tube cutting device 6, and drawn out. The drawing force is imparted by rolls 8 or a capstan (not shown) disposed between 6 and 7. This device 6 consists of two cutting bites 14 arranged symmetrically to each other as shown in FIG. 6, and is adapted to cut the outer metal 3 on both sides of the composite wire near to core filaments 1 inside the outer tube so that the composite wire has a section as shown in FIG. 3. The outer tube metal is cut to an extent as close as possible to the core filaments but without exposing the filaments even at points 3" which are the deepest cuts. For example, when the thickness of the composite wire between the cut surfaces is 0.48 mm, a layer of the outer metal tube having a thickness of 0.010 to 0.015 mm remains.

The composite wire 4 in which the outer layer on both sides have been cut is rolled by rolls 8 slightly to press the upper and lower uncut surfaces. At this time, it is necessary to provide a guide 7 which prevents the composite wire 4' from tumbling down towards the entry side of rolls 8.

By this rolling, the composite wire is collapsed upwards and downwards, and tends to spread laterally and become a fiat wire. Since the surfaces of the core filaments have previously been coated with a separator such as metal oxides, graphite or metal soap, the filaments slip over each other, and are not deformed plastically. Hence, this stress inducing the lateral spreading to form a flat wire is concentrated on the thinnest points 3" of the outer metal as shown in FIG. 3, and these points are broken. Thus, by the rolling operation, the outer tube metal is divided into the upper and lower portions 3 and 3' and is separated from the core filaments 1'. If the rolling force at this time is excessive, the core filaments are plastically deformed to collapse. If, on the other hand, the rolling force is small, the continuous break of the outer tube metal does not occur. Therefore, the rolling conditions should be determined optionally by experiments in relation to the cutting conditions in the previous step.

The two divided outer metal portions 3' and a filament yarn 1 are separated by separating guide rolls 9 into a yarn of fine metallic filaments 1' and two outer metal portions 3', and coiled up by take-up reels 11, 12 and 13. The yarn of fine metallic filaments 1 thus taken up is in the state of being completely separated into the individual filaments as shown in FIG. 4. This is due to the effect of the separator pre-coated on the surfaces of the material wires.

A take'up device 10 having the take-up rolls ll, 12 and 13, for example, is of a slip-type take-up mechanism, or of a mechanism using a fixed torque motor, whereby the yarn and outer metals are coiled up in synchronous relationship with the speed of rolling while a certain prescribed tension is being imparted to the yarn and outer metal.

The above-described apparatus and method makes it possible to remove the outer tube metal from the composite wire containing fine metallic filamentstherein by cutting and rolling and thus obtain a yarn of fine metallic filaments.

Since according to the present invention the separation treatment of fine metallic filaments in the bundle drawing method can be performed by a mechanical procedure using a simple apparatus without carrying out a troublesome and expensive chemical or electrochemical treatment, the operation is simple and the treatment time is shot. Furthermore, because no cost is necessary for chemicals, the method has the advantage that the cost of. production becomes lower. In the conventional method, the outer tube metal is dissolved in a chemical as a result of the chemical or electrochemical treatment, the recovery of the metal must be effected, for example, by electrolytic deposition or precipitation based on the formation of hydroxides, and therefore, generally becomes difficult and expensive. By contrast, in the present invention, it can be recovered as metal quite simply. Hence, when an especially expensive metal such as copper or nickel is used as the outer tube metal, the cost of production can be greatly curtailed.

The invention will now be illustrated further by the following Examples.

EXAMPLE 1 Final composite wire Outer tube metal: mild steel Fine filament: 0.8 percent carbon steel Diameter of the composite wire: 0.60 mm Diameter of each filament (average): 0.050 mm Number of filaments: 91

Thickness of the tube (average): 0.060 mm Separator on the filament surfaces: talcum powder The composite wire shown above was processed by an apparatus of the type shown in FIG. 5. The outer tube metal of the composite wire was cut continuously with application of a cutting oil so that the cut margin became 0.035 to 0.040 mm. Subsequently, the wire was slightly rolled by 6 high rolls in which the diameter of the working roll was 30 mm, and the outer tube metal was divided into two portions. These divided portions and a yarn of the fine metallic filaments therein were separately taken up. A yarn of 91 fine metallic filaments with a diameter of 0.05 mm was continuously obtained at a speed of m/min.

EXAMPLE 2 Final Composite wire Outer tube metal: mild steel Final filament: 304 type stainless steel Diameter of the composite wire: 0.71 mm Diameter of each filament (average): 0.035 mm Number of filaments: 300

Thickness of the tube (average): 0.050 mm Separator on the filament surface: talcum powder The composite wire shown above was cut by the salsa apparatus and method as used in Example 1 except that the cut margin was 0.020 to 0.025 mm. The subsequent procedure was the same as in Example 1, and a yarn of 300 fine metallic filaments having a diameter of 0.035 mm was obtained at a speed of I00 m/min.

What is claimed is:

,1. In a method of producing fine metallic filaments which comprises covering a bundle ofa plurality of material wires with an outer tube metal to form a composite wire, drawing the resulting composite wire and if desired, heat-treating the composite wire, and removing said outer tube metal to provide said fine metallic lilaments, the improvement which comprises removing said outer tube metal by cutting the outer tube metal of the composite wire on both sides near to the core filaments in the composite wire, then rolling slightly to respect to right and left; then exerting a rolling force on the composite wire upwardly and downwardly in a direction parallel to the surface to be cut by means of rolls arranged in tandem thereby dividing the outer tube metal continuously into two portions; and thereafter, separating the outer tube metal and a yarn of fine metallic filaments therein from each other and taking each up separately. 

1. In a method of producing fine metallic filaments which comprises covering a bundle of a plurality of material wires with an outer tube metal to form a composite wire, drawing the resulting composite wire and if desired, heat-treating the composite wire, and removing said outer tube metal to provide said fine metallic filaments, the improvement which comprises removing said outer tube metal by cutting the outer tube metal of the composite wire on both sides near to the core filaments in the composite wire, then rolling slightly to press the uncut surfaces of the composite wire thereby to divide the outer tube metal of the composite wire continuously and to separate fine metallic filaments therefrom.
 2. The method of claim 1, wherein the method comprises passing the composite wire containing a plurality of fine metallic filaments not metallurgically bonded to each other and being covered by the outer tube metal between two opposing cutting bites to cut a part of the outer tube metal in a straight line symmetrically with respect to right and left; then exerting a rolling force on the composite wire upwardly and downwardly in a direction parallel to the surface to be cut by means of rolls arranged in tandem thereby dividing the outer tube metal continuously into two portions; and thereafter, separating the outer tube metal and a yarn of fine metallic filaments therein from each other and taking each up separately. 